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The FD-400 Series ultrasonic
doppler flowmeters measure the
flow of liquids that contain sound
reflectors, suspended solids, or gas
bubbles larger than 100 microns.
These sophisticated instruments
automatically adjust filtering and
gain settings to produce reliable
readings in a wide range of liquid
and reflector conditions.

The FD-400 flowmeter transmitts
ultrasonic sound through the pipe
wall or from the probe tip into the
flowing liquid by using piezoelectric
crystals contained in the transducer
and probe tip. The sound is then
reflected by sonic reflectors
suspended in the liquid and
recorded by the receiver. If the
sonic reflectors are moving within
the sound transmission path, sound
waves will be reflected at a
frequency shifted (Doppler frequency)
from the transmitted frequency. The
difference between the 2 frequencies
is directly proportional to the speed
of the sonic reflectors, resulting in a
liquid flow rate that is converted to
various user-defined units.

Configuration of the FD-400 is
accomplished via the front-panel
keypad. A 2-line backlit LCD displays
rate and total in user-selected units.
Power supply options include AC
and DC. Optional outputs include
4 to 20 mA, relays, and rate pulse.

Two transducer styles are available.
The FD-400C clamp-on, non-intrusive
transducer is recommended for most
metal or plastic pipes. The FD-400C
has an IP68 (NEMA 6P) rating and is
available in a high-temperature
version, “HT”. The user can place
these clamp-on transducers up to
300 metres from the display
enclosure. The FD-400I insertion
probe transducer should be used
on piping systems that do not
permit ultrasonic penetration. The
FD-400I inserts into the pipe wall
and comes into direct contact with
the flowing liquid.